Echo indigo question

I recently purchased an Echo Indigo (a PCMCIA card which replaces the interal DAC and headphone jacks of a laptop see: http://www4.tomshardware.com/game/ [...] dex.html).

Unfortunately, I get frequent clicks and pops when listening to music through the Indigo, and the audio occasionally just stops entirely (until I remove and re-inset the card). I get this problem in WinDVD, Windows Media Player 9, and winamp. System sounds do not play clearly through the Indigo, either (they make a buzzing noise in the headphones). My system is a Compaq Presario 2800T laptop (1.7 GHz, 512 MB ram, WinXP Pro SP1). I've tried disabling the internal audio chip (Soundmax from Analog Devices), and this does not help.....

Does anyone know what else I could do to correct this? I've never had this problem with my internal audio system, I've not heard anything back from Echo....

Thanks!
Dave